Our goal is to develop a novel peptide therapeutic to alleviate brain and vascular injury after hemorrhagic and ischemic stroke. Vascular injury is a leading cause of death in the United States, with approximately 795,000 Americans suffering stroke, with 137,000 deaths each year [1]. Those who survive are frequently disabled, resulting in over one million US stroke victims living with varying degrees of impairment in the US alone [2]. These statistics translate into actual costs to healthcare systems and in lost productivity. I 2010, costs attributed to stroke were $36.5 billion, and that figure is projected to reach $184.1 billion by 2030 [3]. In vascular injury, including hemorrhagic and ischemic stroke, one of the key damaging factors results from the breakdown of red blood cells and hemoglobin. As an oxygen carrier, hemoglobin is essential to our survival. However, in vascular injury, the hemoglobin breakdown leads to the release of toxic levels of hemin. This excess hemin sets off a series of events that are deleterious to the injury site and cause the death of neuronal cells. A potential solution to this damage is a peptide therapeutic agent that would serve as a high-capacity scavenger of the toxic hemin released due to hemoglobin breakdown in bleeding events. Recently, Ewa Bienkiewicz's research group at Florida State University demonstrated that a N-terminal peptide fragment from the prion protein, OR2, can sequester toxic hemin and reduce neuronal cytotoxicity and improve neurofunction in intracerebral hemorrhage mouse model. These findings provide the basis for the development of a novel peptide therapeutic to be used following stroke. Since OR2 is derived from a protein involved in stroke defense mechanisms, this peptide can be thought of as a boost to the natural response our bodies use to combat damage triggered by vascular injury. A second peptide, called A-OR2, has been designed to bind hemin more efficiently than OR2, and provide greater efficacy to reduce neuronal damage than OR2 following bleeding due to stroke. The objective of this proposal is to complete biophysical and functional characterization of OR2 and A-OR2, and select one to advance into clinical development. The proposed SBIR Phase 1 studies have three specific aims: 1) determine the hemin-binding efficacy of A-OR2 compared to OR2 using biophysical methods; 2) establish a cell-based potency assay for measuring the efficacy of OR2-based peptides; and 3) demonstrate that A-OR2 is more effective than OR2 at reducing brain damage in an intracerebral hemorrhage mouse model.